Hot Cams dont seem to fit.


23 replies to this topic
  • Parx_400

Posted April 24, 2005 - 07:19 PM

#1

I am trying to install a set of hot cams on my bike and they dont seem to spin as free as the stock ones when the cam holder in torqued down. it seems like a very tight fit where the barring sits in the head. plus the stock clips dont seem to stay in place. HELp some one i suck at these things and it is my first time.

  • cowboyona426

Posted April 24, 2005 - 09:35 PM

#2

Try loosening the cam cap bolts a little, the cams should be able to spin freely with the caps installed. Also, double check to make sure you got the right cams.

  • Daz_426_02

Posted April 24, 2005 - 11:59 PM

#3

Also check the two cams next to each other for a good comparison.
You say they aren't turning as easily? Is that with the cams torque down? Are you using a torque wrench? Also when fitting the new cam make sure to put a healthy amount of engine oil where the bearings run for the start up.

Good luck

  • FFRacing79

Posted April 25, 2005 - 04:14 AM

#4

I have found that even some of the stockers don't spin free when new. The book calls for 7-8 ft/lbs torque but I only go to 5(60 in/lbs). I just put them in the lathe and polish the journals till they spin free. If they don't spin free, it is possible they might gall. Tdub

  • sirthumpalot

Posted April 25, 2005 - 04:45 AM

#5

I am trying to install a set of hot cams on my bike and they dont seem to spin as free as the stock ones when the cam holder in torqued down. it seems like a very tight fit where the barring sits in the head. plus the stock clips dont seem to stay in place. HELp some one i suck at these things and it is my first time.


USE A GOOD TORQUE WRENCH! Too tight and as stated above this may end in a bad way.

  • Parx_400

Posted April 25, 2005 - 05:42 AM

#6

i used a torque wrench but it is not all that good. and i did it to the specs both yamaha and hot cams said. i put oil on the new cams but maybe not enough.

  • Dolce_Grappa

Posted April 25, 2005 - 05:46 AM

#7

I have found that even some of the stockers don't spin free when new. The book calls for 7-8 ft/lbs torque but I only go to 5(60 in/lbs). I just put them in the lathe and polish the journals till they spin free. If they don't spin free, it is possible they might gall. Tdub



Are you sure the book say's "7-8ft/lbs" I don't have the book in front of me, but I believe it's 8Nm which is ruffly 6ft/lbs.

Secondly - are your bolts oil free or do you have oil on them? If they're lubed you need to multiply your torque by .80 then use that figure and 5ft/lbs will work.

72in/lbs x .8 = 57.6

  • Parx_400

Posted April 25, 2005 - 06:10 AM

#8

yes they had oil on them. i will try 5 ft pounds when i gt home, thanks guys.

  • MNellis

Posted April 25, 2005 - 07:31 PM

#9

If in doubt, follow the manul and get some plasti-guage from your local auto supply store and check the cam journal clearance. I don't have the spec's in front of me but it's a pretty tight fit, less than .001" if I recall.

Be sure and use some Moly Lube on the journal and cam face when installing the cams if you've done a rebuild and the oil pump is dry.

  • yz426onNOS

Posted April 25, 2005 - 07:56 PM

#10

I had the same problem when I had the head machined on my 426. I took it back to the head builder and he fixed it. I cannot remember what the problem was. But it was the same thing that happened to you. When I would torque it down they would not spin. All I can say is something is binding somewere.

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  • DigilubeJay

Posted April 26, 2005 - 02:58 AM

#11

Be sure and use some Moly Lube on the journal and cam face when installing the cams if you've done a rebuild and the oil pump is dry.

Much of our motor oil contains a small amount of moly, but using a moly lube you are introducing massive amounts of moly that could possibly cause clutch plates to slip. If you do use a moly lube for a rebuild lube, use it sparingly and only apply a thin film.

  • Dolce_Grappa

Posted April 26, 2005 - 05:21 AM

#12

Much of our motor oil contains a small amount of moly, but using a moly lube you are introducing massive amounts of moly that could possibly cause clutch plates to slip. If you do use a moly lube for a rebuild lube, use it sparingly and only apply a thin film.


Has anyone tried straight STP motor treatment for an engine rebuild? I know a lot of old timers that used it for build stock cars motors and it has all the good stuff that meets the JASO requirement and is extremely viscous and slippery.

  • Parx_400

Posted April 26, 2005 - 08:23 PM

#13

even at 5ft pounds its still tight. i am going to check the oem and the hot cam size to see if the hot cam is made wrong. (out of spec)

  • FFRacing79

Posted April 27, 2005 - 04:11 AM

#14

even at 5ft pounds its still tight. i am going to check the oem and the hot cam size to see if the hot cam is made wrong. (out of spec)


Try it with the shims out...might have one that is just to tight. If that isn't the problem, just polish the cam wherwe it rides in the journal. No big deal to do it. Tdub

  • Parx_400

Posted April 27, 2005 - 04:31 AM

#15

ok glad to know its ok to do that. i have a guy across from my work that can builds engines and can do that for me. the shims i know are not that problem, i checked and they are all loose and out of spec. it has to be the journals or the bearing. i will check it next to the oem today and see what i find. thanks for all the help guys.

  • sirthumpalot

Posted April 27, 2005 - 05:16 AM

#16

.....Secondly - are your bolts oil free or do you have oil on them? If they're lubed you need to multiply your torque by .80 then use that figure and 5ft/lbs will work....


Where does this info come from? I've never heard this before. :naughty:

  • Parx_400

Posted April 27, 2005 - 05:34 AM

#17

Not sure, but the guys at hot cams said to use 5 ft pounds too.

  • Scotty426

Posted April 27, 2005 - 07:03 AM

#18

You can get a cheap dial caliper from the local auto parts store and measure both cam journals or take them (both cams) to a machine shop to get them "miked". PLEASE TELL ME YOU REDID THE CAM BUCKET SHIMS. That is super important and will eventually destroy the bucket if not right (.2mm exhaust). There is a cam spec sheet with the cam that will tell you the base circle dimension as well as lift and duration. Check it to see if it matches with the dial caliper. For the record, my hotcams exhaust cam slid in easy, spun fine lit on the second kick. Runs great. You say the retaining clip doesn't fit. Why? No groove? Groove is too big? Do your cam retainers/towers have the seating dowels still in place? If they are lost, you can bolt them down too far forward or back. It doesn't take much. Either way, good luck to you Brother.

  • DigilubeJay

Posted April 27, 2005 - 06:40 PM

#19

Where does this info come from? I've never heard this before. :naughty:

A bolt that is lubricated with grease or a anti-seize compound creates less friction than a non-lubricated bolt. So, with the same amount of force, the lubricated bolt will obviously turn further than the non.

The lubricated bolt will turn approx. the same amount of distance as the non-lubricated bolt by using only ~80% of the force needed to turn the non-lubricated bolt that distance.

  • Dolce_Grappa

Posted May 01, 2005 - 12:18 PM

#20

Where does this info come from? I've never heard this before. :naughty:


I picked this info up at a Diesel Trade school I went to many years ago. Your torque coefficients change when any lubricants are applied, also you can run into a hydraulic lock state. Our factory manual show most fasteners are dry assembled, unless otherwise noted.

There's a good pocket reference book called, none other than "Pocket Ref" by Thomas J. Glover.





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